ios - how to specify height of row? -

i want implement tableview shows expandable cell specific row, create custom table cell expanded if setting expandcontent following:

- (uitableviewcell *)tableview:(uitableview *)tableview cellforrowatindexpath:(nsindexpath *)indexpath {     static nsstring *cellidentifier = @"cell";     customcell *cell = [tableview dequeuereusablecellwithidentifier:cellidentifier];     nsstring *shouldexpand = [self.datasource objectatindex:indexpath.row];     if([shouldexpand isequaltostring:@"expand"]){         [cell setexpandcontent:@"expand"];     }     else{         [cell settitle:@"a line"];     }     return cell; } 

however, in order tell tableview row height, need implement following code:

- (cgfloat)tableview:(uitableview *)tableview heightforrowatindexpath:(nsindexpath *)indexpath {     customcell *cell = [self tableview:tableview cellforrowatindexpath:indexpath];     return [cell cellheight]; } 

the problem heightforrowatindexpath method call 1000 times of tableview:cellforrowatindexpath: if datasource contains 1000 data, , cost time.

how fix problem?

no u should find size of cell first send hight calculated, dont call tableview:cellforrowatindexpath: results in recursion instead, first calculate , send height . example

         //say suppose placing string inside tableview cell u need   calculate cell example      nsstring *string = @"hello world happy coding";     cgsize maxsize = cgsizemake(280, maxfloat);//set max height      cgsize cellsize = [self.str sizewithfont:[uifont systemfontofsize:17]                    constrainedtosize:maxsize                    linebreakmode:nslinebreakbywordwrapping];//this return correct height text     return cellsize.height +10; //finally u return height